The present invention pertains to microwave signal generating sources, such as magnetrons, klystrons, traveling-wave-tubes, and solid state sources. Most of these sources, and especially the magnetron, suffer from lack of frequency stability due to temperature and pulse repetition frequency (PRF) changes. In many instances, the instability is so severe, the source is out of specification and must be discarded.
In general, there are three types of prior art stabilization:
1. High Q cavity stabilization, which is difficult to implement due to the size and complexity of microwave cavities, and is, therefore, very expensive. Further, such cavities generally have an inherent insertion loss which is undesirable because of the reduction in power.
2. Injection locking to a stable reference source, which is also complex and expensive because of the size. This method requires power consumption. Further, some sources, such as those mentioned above, are too high in RF output power to be injection phase locked by a stable reference source.
3. Phase locked loops, which is the most costly and technically complex method. This method also requires the most area and greatest number of components.